No need to read full RowGroup when using RowRanges
- Dominant language
- Java
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Description
### Describe the enhancement requested
I'm using ParquetFileReader and would like to read the few first line of a parquet file to show a preview to the user.
I'm doing this :
PageReadStore rowGroup = reader.readFilteredRowGroup(0, RowRanges.createSingle(10));
and then :
ColumnReadStore colReadStore = new ColumnReadStoreImpl(rowGroup,
new GroupRecordConverter(schema).getRootConverter(),
schemaLecture, ...);
etc.
The problem is when calling readFilteredRowGroup(), it reads the full row group in memory, which in my case is slow because the parquet file is on a network drive and has quite big row group. On top of that, it consumes RAM for nothing.
Is this an issue or could it be improved ?
Thanks in advance.
Olivier
### Component(s)
_No response_
Contributor guide
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Research direction
Start at ParquetFileReader.readFilteredRowGroup() and trace how RowRanges.createSingle(10) is handled when loading a row group. Determine where the full row group is read and how range filtering could limit network reads and memory use; done means the requested rows can be read without loading the full row group.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- data-engineering
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100